Grouting compositions have been used for many years to minimize movement of water or other fluids into, through and out of wells and other subsurface cavities. Grouts have also been used to limit the movement of water and other fluids into buried foundations and other subsurface structures. Grout compositions incorporating bentonite are known to exhibit the characteristic of low permeability to fluids. In these compositions the degree of impermeability is directly related to the amount of bentonite present. Prior to the development of this invention, high concentrations of bentonite in grout mixtures have made the mixtures rapidly become too thick, viscous and/or sticky to be useful. Such mixtures can quickly clog pumping equipment and related conveying hoses and pipes, making them unusable.
Mason, U.S. Pat. No. 4,463,808 describes a composition in which bentonite, especially granular bentonite, or other water swellable clay is added to a premixed water and polymer solution The polymer is a water dispersible hydrolyzed polyacrylamide which inhibits the swelling of the clay for a sufficient period of time to allow the fluid grout thus produced to be placed at the desired location in the well borehole. Granular bentonite is stated to be particularly desirable for use in this composition because finely ground bentonite swells more rapidly and must be more rapidly emplaced in the well bore. The amount of bentonite indicated for this composition is from 2 to 4 pounds per gallon of water.
Messenger, U.S. Pat. No. 2,861,636, describes a clay cement including silica, alumina or silica-alumina and a water soluble phosphoric acid salt. Hughes, U.S. Pat. No. 3,986,365, describes use of a three-part mixture of soil, bentonite and very high molecular weight viscosifying polymer for forming an enclosure and sealing a water-holding area. The viscosifying polymer allows the amount of bentonite to be reduced.
Armentrout, U.S. Pat. No. 3,028,913, discloses a non-reswellable sealant composition for recovering lost circulation in wells. The composition includes hydratable material, inhibitor and a delayed action accelerator. Caron, U.S. Pat. No. 3,111,006, discloses a composition for injection into soil, including swellable clay and additives necessarily including alkali silicates.
Harriett, U.S. Pat. No. 4,696,698, 4,696,699 and 4,797,158 describe grouting compositions containing 10 to 80% bentonite or other water swellable clay, 10 to 80% non-swelling particulate filler such as fly ash, diatomaceous earth or calcined clays, 0.5 to 35% water soluble silicates as solidifiers, 0.5 to 35% gelling agent and 0.5 to 35% multivalent cation source. This composition optionally also includes 0.5 to 5.0% sodium pyrophosphate as a dispersing agent for the water swellable clay. Harriett cautions against the use of polymer treatment of the water swellable clay, using salts of polyacrylic acid or other polymer agents, in order to avoid premature gelling of the composition.
Alexander, U.S. Pat. No. 4,886,550, describes a flexible grouting composition and method including 80.0 to 99.5% water-swellable clay, 0 to 20% solid, particulate filler and 0.5 to 20.0% dispersing agent for the water-swellable clay, particularly an inorganic dispersing agent such as sodium acid pyrophosphate.